Microsoft Releases MS-DOS 4.0 Source Code on GitHub

In a nostalgic move, Microsoft, in partnership with IBM, has opened the source code of MS-DOS 4.0 under the MIT license, marking another step in preserving software history.

Microsoft collaborates with IBM to release the MS-DOS 4.0 source code, over 35 years after its initial launch.
The release includes not only the source code but also floppy disk images and documentation, now accessible on GitHub.
MS-DOS 4.0, known for its high memory usage and bugs, was part of Microsoft's early attempts at multitasking in operating systems.
The open-source community can now explore MS-DOS 4.0 using emulators like PCem and 86Box, or even on original hardware like the IBM PC XT.
Future plans include releasing the source codes of other MS-DOS versions, enhancing the availability of historical software versions.